Flux-Cored Wire Composition for Offshore Welding Toughness

The patent changes the chemical composition parameters of the flux core, specifically controlling TiO2 content at 3-8 mass%, Si content at 0.1-0.5 mass%, C content at 0.01-0.15 mass%, and Mn content at 0.5-3.0 mass%. These parameter adjustments optimize the weld metal chemistry to achieve both high welding efficiency and improved low-temperature toughness by reducing oxygen content while maintaining productivity.

The patent creates a composite flux composition combining multiple materials with complementary functions: TiO2 (3-8 mass%) for slag formation and deoxidation, Si (0.1-0.5 mass%) for viscosity control and deoxidation, C (0.01-0.15 mass%) for reducing oxygen content, Mn (0.5-3.0 mass%) for strengthening and deoxidation, Mo (0.01-0.80 mass%) for high-temperature strength, Ni (1-3 mass%) for toughness, Mg (0.2-1.0 mass%) for deoxidation, F compounds (0.01-0.400 mass%) for hydrogen removal, K compounds (0.01-0.400 mass%) for arc stability, Na compounds (0.005-0.400 mass%) for slag fluidity, and B (0.001-0.005 mass%) for grain boundary strengthening. This composite approach enables all-position welding while achieving comprehensive cracking resistance and toughness.

The patent optimizes the balance between strength and toughness by precisely controlling alloying element parameters: C content at 0.01-0.15 mass% provides sufficient strength without excessive hardening, Mn content at 0.5-3.0 mass% offers strengthening through solid solution and precipitation hardening while maintaining ductility, Mo content at 0.01-0.80 mass% enhances high-temperature strength and hardenability, and Ni content at 1-3 mass% improves toughness and resistance to brittle fracture. This parameter optimization achieves yield strength of 620 MPa or more while maintaining Charpy impact value at -60°C of 27 J or more.